Hi all, I learned much from u all in the passed one year, it's my hounor to be a member of 6lowpan group, It's a promissing team. I am leaving school soon, and will no longer work on 6lowpan, so, do any body know how to quit from 6Lowpan group? or, would the admin be kindly to remove me from the member list? thanks, yan
From: "Muneeb Ali" <[EMAIL PROTECTED]> To: "Philip Levis" <[EMAIL PROTECTED]> Date: Sat, 8 Dec 2007 06:54:14 +0800 (CST) Subject: Re: [6lowpan] ND optimization for sensor nodes (power saving / Idle/Sleep mode) On 12/7/07, Philip Levis <[EMAIL PROTECTED]> wrote: On Dec 6, 2007, at 4:39 PM, Timothy J. Salo wrote: > > Do any of the 802.15.4 chips support a "wake on receive" > capability? Does this capability (assuming it exists) > require that the radio be powered on continuously? That is, > does this capability power-down _only_ the processor, but > not the radio? Does this capability really save enough > power to meet the needs of many battery-powered, hopefully > long-lived wireless sensor networks? > This doesn't work like you think it does. To hear a signal, your radio has to be on. The energy cost of demodulation is not the principal issue. Phil Yes, to hear a signal the radio needs to be on. So "wake on receive" is hard unless you consider dual radios. The concept of "dual radios" has existed in theory. A second, always-on, radio can wake up the "main" radio to give you wake on receive functionality. However, the power consumption of the always-on second radio will cost you a lot more (in terms of energy) compared to duty-cycling the "main" radio. Thats why dual radios with wake-on-receive have largely remained a theoretical concept. See this work http://www.st.ewi.tudelft.nl/~koen/papers/wakeup-radio.pdf for a working prototype of a dual radio (EUR 5 per radio) that has acceptable energy costs in always-on mode. The current problem, however, is that the range of the wake-up radio is fairly small. Second problem is that to keep the energy costs low, you will end up with a "bare-bones" radio that is not even sophisticated enough to do addressing. You end up waking up a lot of neighbors if you don't know how to address a particular one (don't know if they have already solved this). Increasing the range while keeping energy costs acceptable is an on-going work at the startup from where one of the authors is from. _______________________________________________ 6lowpan mailing list [email protected] https://www1.ietf.org/mailman/listinfo/6lowpan -- Cheers, Muneeb Ali | http://muneeb.org
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